The first round of nanostreams had some problems relating to their casings from some error in casting them. There were also some issues about the impeller not mounted properly in the drive, but the majority of complaints seem to be related to some noise when turned on until the propeller started to spin in the right direction. I read from the tunze support forum that all new pumps being shipped have been have been cast (or whatever the process is called) at the correct temp for the plastic used, and I've seen that tunze has stood up and taken responsibility and are taking back any pump that have any potential defect for replacement. I held off on ordering until I could order from the new revision batch and I'm waiting on a 6025 nanostream to arrive. I hope the defective casting issue is resolved. I'm not expecting any noise issues, and now I know that the rattle at startup is normal for around 15 seconds until the propeller it's turning in the right direction.
You really might want to look at the 6055s' when they arrive, as they can be used on a controller, and will be a lot cheaper than the turbelles. In truth, I would think 2 of them in a 50g would be fine, and I agree with you that the turbelles would be overkill.
Henry
Probably not drawing enough power.
